Psychology, School of Social Sciences, Nanyang Technological University, Singapore.
Centre for Research and Development in Learning (CRADLE), Singapore.
Brain Lang. 2020 Nov;210:104850. doi: 10.1016/j.bandl.2020.104850. Epub 2020 Sep 2.
tDCS can modulate reading which is processed by lexical (ventral) and sub-lexical (dorsal) pathways. Previous research indicates that pathway recruitment in bilinguals depends on a script's orthographic depth and a reader's proficiency with it. The effect of tDCS on each reading pathway has not been investigated in bilinguals. We stimulated the left dorsal and ventral pathways separately in Chinese-English (C-E) bilinguals to understand whether pathway-specific modulation by tDCS is possible and, if so, how it is influenced by orthographic depth and script proficiency.
A double-blind, sham-controlled, within-subject experiment was designed wherein 16 balanced bilinguals received anodal tDCS in dorsal, ventral and sham sessions. Two tDCS montages of electrode sizes 5 × 5 cm with 1) anode at CP5 and cathode at CZ, and 2) anode at TP7 and cathode at nape of the neck, were applied for stimulating the dorsal and ventral pathways respectively. Bilinguals were asked to read word lists for each language before and after stimulation. RTs for accurate trials were analysed using linear mixed-effect modelling that included proficiency scores for reading English pseudo-words (PW) and Chinese pinyin.
For both languages, word reading RTs were faster following dorsal pathway stimulation. The dorsal stimulation effect (change in RT) was negatively correlated with pseudoword reading and pinyin proficiency. Stimulation of the ventral pathway decreased RTs only for Chinese reading.
Dorsal and ventral reading pathways can be selectively modulated by tDCS in bilingual readers with dorsal (sub-lexical) pathway stimulation affecting reading in both scripts and ventral (lexical) pathway stimulation selectively affecting Chinese reading. Dorsal pathway tDCS effects are modulated by sub-lexical reading proficiency.
tDCS 可以调节阅读，阅读是由词汇（腹侧）和亚词汇（背侧）通路处理的。先前的研究表明，双语者的通路募集取决于脚本的正字法深度和读者对其的熟练程度。tDCS 对每种阅读通路的影响在双语者中尚未得到研究。我们分别刺激中国-英语（C-E）双语者的左背侧和腹侧通路，以了解 tDCS 是否可以对通路进行特异性调节，如果可以，其受正字法深度和脚本熟练程度的影响如何。
设计了一项双盲、假对照、单内体实验，其中 16 名平衡双语者在背侧、腹侧和假刺激会话中接受了阳极 tDCS。使用两种大小为 5×5cm 的电极刺激背侧和腹侧通路：1）阳极位于 CP5，阴极位于 CZ；2）阳极位于 TP7，阴极位于颈后。要求双语者在刺激前后阅读每种语言的单词列表。使用线性混合效应模型分析准确试验的 RTs，其中包括阅读英语伪词（PW）和汉语拼音的熟练程度得分。
对于两种语言，背侧通路刺激后单词阅读 RTs 更快。背侧刺激效应（RT 变化）与伪词阅读和拼音熟练程度呈负相关。腹侧通路刺激仅降低了中文阅读的 RTs。
tDCS 可以选择性地调节双语读者的背侧和腹侧阅读通路，背侧（亚词汇）通路刺激影响两种脚本的阅读，腹侧（词汇）通路刺激选择性地影响中文阅读。背侧通路 tDCS 效应受亚词汇阅读熟练程度的调节。
